That rule (which has since been changed) only applied IF Zero was born outside the United States. IF he was born on US soil, her age was of no consequence, and she could have conveyed US citizenship to him. That is why they had to fabricate the two phony birth certificates.
Of course it (his mother's age requirement) doesn't apply if he was born in the US, but there has been no birth certificate presented to prove that he was born here.
And then, if it is proven that he was born on US soil, he still is ineligible because of the status of his father as a British citizen.